Top Smart Thermostats for Preference and Usability Karen Herter, Ph.D. Why Thermostats Matter Thermostats manage ~25% of annual electricity use at SMUD Residential AC is responsible for >30% of SMUD peak October 20, 2015 Powering forward. Together. Source: California Energy Commission, 2009 2 Why Smart Thermostats Matter Why Smart Thermostats Matter Source: Herter Energy, SMUD s Load Impact Calculator 3 Source: Herter Energy, SMUD s Load Impact Calculator 4 1
Thermostats Tested (2013) Research Questions Lux Smart Temp (Non-communicating) Honeywell FocusPro (Non-communicating) RCS TZ-45 Radio Thermostat CT30 1. How do thermostats compare in terms of: Efficiency (time-on-task) Nest Computime CTW218 Carrier Comfort Choice Touch Ecobee Smart Si Preference (of two tested thermostats) Satisfaction (ratings of standard features) 2. How do participants rate advanced features? Energate Foundation Energate Pioneer Z100 Cooper-Honeywell Utility Pro Emerson Smart Energy 5 6 Methodology Laboratory Layout 12 thermostats tested 10 communicating smart thermostats (6 with apps) 2 standard non-communicating thermostats Simultaneous multi-user, paired-comparison test 163 participants x 2 units per participant = 326 tests >95% of possible ordered pairs tested 90-minute sessions Video recording of thermostat tests Surveys Group discussions 7 8 2
Efficiency = Time on Task Results: Efficiency The same 7 tasks were performed for each thermostat 1 Identify the current indoor temperature 2 Set to cool. Identify the current target cooling temperature 3 Change the current target cooling temperature to 79 4 Identify the scheduled cooling temperature for Saturday at 8 am 5 Set to heat. Identify the current target heating temperature 6 Change the current target heating temperature to 63 7 Identify the scheduled heating temperature for Saturday at 8 am 9 10 Preference Results: Preference Imagine that the thermostat in your home suddenly dies and your mechanic offers a choice between the thermostats you just reviewed - at the same price. Please circle the thermostat you would choose to have installed. 6 2 11 12 3
Satisfaction (with Standard Features) Results: Satisfaction 13 14 Regression of Standard Features Ratings on Efficiency and Preference Screen Color display higher Preference scores Larger screen higher Efficiency scores Perceived Usefulness of Potential Advanced Features Feel and Sound Participant Characteristics Smart Phone App Appearance Number of Buttons Higher Feel & Sound ratings higher Preference Youth higher Efficiency scores Home owners higher Efficiency scores Not significant in predicting efficiency or preference Rated higher by younger users Not significant Not significant 15 16 4
Top Ranking Smart Thermostats 2013 Thermostats being Tested (2015) 1. Carrier Comfort Choice Touch ecobee3 Honeywell Lyric Honeywell RTH9320WF Emerson Sensi 1. Emerson Smart Energy Venstar ColorTouch Trane XL824 Lux GEO Carrier Cor 1. Ecobee Smart Si 17 Nest 3rd generation Schneider Wiser Air American Standard AZone950 Allure Eversense U.S. Department of Energy Disclaimer Questions? Full report available at: Acknowledgement: This material is based upon work supported by the Department of Energy under Award Number OE000214. www.herterenergy.com/pdfs/publications Disclaimer: This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Contact: Vikki Wood 916-732-6278 VWood@smud.org Karen Herter 916-397-0101 Karen@HerterEnergy.com 19 5